Lake Ouachita has lots of dive sites with visibility that ranges from 35' or more under ideal conditions (usually early spring and late fall) to 3 - 5' under adverse conditions. Generally the Eastern half of the lake (nearer the dam) will be clearest. Boat scuba tours are available on weekends from Rick's Dive and Travel Center in Little Rock during weekends in the summer months.
http://www.ricksdivecenter.com/take_dive/take_dive_index.html
A full range of supplies (Air / Training / Equipment / Maps) is available at the Lake Ouachita Dive Center (LODC) at the marina at Brady Mountain every day during the summer and on weekends in May and September. For questions you can contact the Scuba and Archery Center in Hot Springs, 501-623-7062.
Other places on the lake that also offer air for tank fills are to be found at Mtn Harbor and Spillway marinas. I am not familiar with them so don't know how extensive their supplies / training availability / etc is.
The campgrounds on Ouachita are great and include a half dozen RV campgrounds and another equal number of free sites with campsites, but no services. Brady Mtn campground has been voted as having the second most scenic campsites in the Reserve America listing which includes over 100,000 US federal campgrounds, national forests, and many state campgrounds throughout the nation.
The following are some of the GPS points that I use on the lake. Others I will post on my website later if there is interest.
Points of interest on Lake Ouachita Starting from
dam. Listed as Degrees and Minutes.xxx'
Dam N34 34.439' W93 11.675' (popular shore access)
Crawdaddy Island N34 36.064' W93 12.148'
Point 02 N34 35.739' W93 14.089'
Brady Ramp (LODive Ctr) N34 35.295' W93 15.423'
Brady Ramp 1 N34 34.922' W93 16.034'
Point 03 N34 34.507' W93 17.183'
Point 04 N34 34.148' W93 18.795'
School Bus (wreck) N34 36.170' W93 18.410' (*)
VW Rabbit (wreck) N34 36.473' W93 18.162' (*)
Bird Island N34 35.698' W93 19.214'
Point 05 N34 34.909' W93 19.743'
Buckville Cmpgnd N34 36.597' W93 20.635'
CS Entry to Chute N34 34.973' W93 20.592'
Crystal Springs Ramp N34 32.579' W93 20.995'
Point 08 N34 33.720' W93 21.450'
Pollard Creek N34 34.634' W93 22.510'
Avant Cmpgnd N34 38.285' W93 23.044'
Big Fir Cmp N34 36.313' W93 24.483'
Mountain Harbor Marina N34 34.535' W93 26.324'
Little Fir Cmp N34 37.987' W93 28.282'
Denby Point Cmpgnd N34 33.179' W93 29.272'
Twin Creeks Cmpgnd N34 33.131' W93 30.753'